Two factors suggest the need for HIV prevention efforts focused on partnered young men who have sex with men (YMSM). First, HIV rates are rising in this population, which already bears a disproportionate burden of HIV infection. Second, main partnerships - rather than casual partners - account for a majority of new infections, and younger age has been associated with an increased risk of main partner transmission. Substance use remains a critical factor associated with HIV sexual transmission risk behavior. Couples based approaches to HIV testing have been developed for gay men [and the CDC has initiated implementation efforts in the US]; however, existing protocols do not include a focus on substance use. In addition, existing protocols are predicated on the assumption that members of the couple possess adequate assertive communication skills to discuss relationship agreements, which may be underutilized by YMSM. The proposed project will develop a novel intervention to reduce substance use and sexual risk behavior among partnered YMSM through the modification of an existing Couples Voluntary Counseling and Testing (CVCT) protocol originally created by Drs. Sullivan and Stephenson (co-investigators). The new intervention protocol (CVCT+SU) will be informed by qualitative data gathered from 20 HIV testing providers and existing qualitative data from 21 gay couples. In addition to the development of the novel CVCT+SU protocol, the project will develop two brief assertive communication training videos (ACTV) specifically for use with partnered YMSM. [The final two years of the project are devoted to a randomized controlled trial (RCT) comparing the new CVCT+SU to the standard CVCT protocol and testing the added efficacy of the ACTV component. A total of 90 couples will be randomized to one of three conditions (standard CVCT, CVCT+SU, or CVCT+SU and ACTV) using a random adaptive allocation strategy executed using Minim software.] All participants will complete a 3 and 6 month follow up. The study team is led by Dr. Tyrel J. Starks (PI), a new investigator with substantial experience in the analysis f dyadic data, who has collaborated on numerous projects examining the nature of sexual agreements and their association with substance use and HIV transmission risk behavior. He is supported by a team of seasoned investigators, including Drs. Sullivan and Stephenson [(leaders in the CDC's US based CVCT implementation efforts)] as well as Dr. Jeffrey Parsons. The team brings extensive experience in qualitative data analysis with couples and individuals, HIV prevention research, and specifically intervention development.